<!DOCTYPE html>
<html lang="en">
    <head>
        <meta charset="UTF-8" />
        <meta http-equiv="X-UA-Compatible" content="IE=edge" />
        <meta name="viewport" content="width=device-width, initial-scale=1.0" />
        <title>原生JS事件绑定</title>
    </head>
    <body>
        <button id="btn1">按钮1</button>
        <button id="btn2">按钮2</button>
        <button onclick="demo()">按钮3</button>
        <script type="text/javascript">
            const btn1 = document.getElementById("btn1");
            btn1.addEventListener("click", () => {
                alert("按钮1被点击了");
            });

            const btn2 = document.getElementById("btn2");
            btn2.onclick = () => {
                alert("按钮2被点击了");
            };

            function demo() {
                alert("按钮3被点击了");
            }
        </script>
    </body>
</html>
